1. Field of the Invention
The invention is related to the handling of covers, namely of sewer or road-manhole covers, or the like. It relates in particular to a tool for handling such covers, which can be referred to as a cover lifter, which should enable an operator to remove such a cover, in order to have access to the manhole or to the sewer, then to re-place it after the inspection.
The invention also relates to a method for removing and re-placing a sewer or road-manhole cover using the cover lifter according to the invention.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
In the field of the tools for handling such covers, tools with hooks have since long been developed, which permit to take hold of the cover at a point of the cover in order to take hold of it with such hooks. Nevertheless, the covers are heavy, up to 70 kg, and their lifting is difficult, even if it is carried out by two persons. Furthermore, the covers are often jammed in their recess, by small stones or tar, which have been introduced into the gaps between the cover and its recess.
EPO 484 285 discloses a tool for handling covers including such a hook, a fulcrum, and a handle, thus permitting to gear down the force for separating the cover. Nevertheless, this tool provides no solution for an efficient removal of the cover, nor for its displacement to one side.
EP2 702 753 discloses a tool for handling covers, also with a hook, a fulcrum and a handle. The tool disclosed in this document permits in a first phase the separation of the cover from its recess (FIGS. 2 and 3), then the effective removal, with the displacement of the cover by means of two tools handled by two operators. Nevertheless, besides the necessity of causing two operators to intervene, the work remains difficult, since the whole weight of the cover has to be carried, then displaced and laid down.
U.S. Pat. No. 7,544,035 discloses a tool for handling covers with a hook and with a magnet. Two magnets are placed on the cover, then a bar with hooks is arranged so as to take hold of the two magnets, and the hook of the tool takes hold of the bar, in order to lift it. Nevertheless, if the magnets are not placed accurately on both sides of the center of gravity of the cover, it is highly likely that the latter tilts during the lifting.
There is thus a need for finding a solution permitting to facilitate the handling of such covers. With the tools of the state of the art, it could indeed be observed that about 20% of the operators have suffered from work accidents, namely with back troubles, or entrapment of fingers.